1. Field of the Invention
The present invention relates to a method for estimating shear wave reflection data from compressional wave reflection data and, more particularly, to a method for producing pseudo-shear wave reflection seismic sections from compressional wave reflection data.
2. Discussion of the Prior Art
The use of compressional (P) wave reflection data in geophysics analysis is notoriously well known. Typically, seismic sections are produced from compressional wave subsurface reflections which provide extremely useful information concerning formation characteristics. Recently, interest has been growing in obtaining shear (S) wave seismic sections which would provide additional useful information concerning subsurface formation characteristics which can be used in conjunction with information obtained from compressional wave seismic sections. For example, P wave seismic sections can provide useful information on the compressibility of subsurface formations, while S wave seismic sections can provide useful information on subsurface formation rigidity. However, the detection of shear wave reflections is more difficult than is the case with compressional wave reflections. The shear wave reflections are typically of lower amplitude than compressional wave reflections, making detection difficult, and the direct propogation of a shear wave into a subsurface formation to induce a shear wave reflection requires special transducers and additional steps over and above those required for obtaining compressional wave reflection data. This makes obtaining shear wave reflection data difficult, more costly and time consuming.